Bag making machine

ABSTRACT

A machine for making bags having cross-bottom end-closures, comprising an end-closure laying station, a delivery station and a diverter disposed between them. The diverter is controlled by end-closure checking means and is effective to reject faulty bags from a conveying path between the stations. The checking means comprises a single row of sensors for checking the presence of oblique edges of inwardly folded corner portions of the endclosures and any deviation in the position of the oblique edges from a predetermined desired position. Only one row of stationary oblique-edge sensors is provided to sense the actual positions of the leading, as well as the trailing oblique edges so that as a bag is being moved along the conveying path, first the leading oblique edges and then the trailing oblique edges come within the sensing range of the oblique-edge sensors, with means being provided to store fault impulses from the oblique-edge sensors and to transmit all fault impulses for any one bag simultaneously to actuating means for the diverter.

United States Patent [72"] lnventors Willi Stork Tecklenburg; Werner Schmalstieg, Lengerigh of Westphalia, both, Germany [211 Appl. No. 825,900 [22] Filed May 19, i969 [45] Patented June 8,1971 [73] Assignee Windmoller & l-lolscher Lengerich of Westphalia, Germany [32] Priority May 22, 1968 [33] Germany P 17 61 466.3

[54} BAG MAKlNG'MACl-IINE 10 Claims, 3 Drawing Figs.

[52] U.S.Cl 93/8 [51.] lnt.Cl B3lb 1/00 [50] Field ofSearch ..93/8, 35,93

[56] References Cited UNITED STATES PATENTS 3,374,714 3/l968 Berghgracht 93/8 3,433,135 3/1969 Lokey et al. 93/8 Primary ExaminerBernard Stickney Attorney-Fleit, Gipple and Jacobson ABSTRACT: A machine for making bags having cross-bottom end-closures, comprising an end-closure laying station, a delivery station and a diverter disposed between them. The diverter is controlled by end-closure checking means and is effective to reject faulty bags from a conveying path between the stations. The checking means comprises a single row of sensors for checking the presence of oblique edges of inwardly folded comer portions of the endclosures and any deviation in the position of the oblique edges from a predetermined desired position. Only one row of stationary oblique-edge sensors is provided to sense the actual positions of the leading; as-- well as the trailing oblique edges so that as a bag is being moved along the conveying path, first the leading oblique edges and then the trailing oblique edges come within the sensing range of the oblique-edge sensors, with means being provided to store fault impulses from the oblique-edge sensors and to transmit all fault impulses for any one bag simultaneously to actuating means for the diverter.

PATENTH] Jun 8 an SHEET 1 BF 2 INVENTORS Willi STORK Werner" SCHMALSTIEG their ATTORNEYS PATENTEU JUN 8197! SHEET 2 BF 2 INVENTORS Willi STORK B Werner SCHMALSTIEG wow their ATTORNEY S BAG MAKING MACHINE The invention relates to an improvement in or modification of the bag making machine forming the subject prior Pat. Application Ser. No. 684,327 dated Nov. 20, 1967, now Pat. No. 3,524,389, issued Aug. l8, I970 which concerns a machine for making bags having cross-bottom end-closures, comprising an end-closure laying station, a delivery station and, disposed between them, a diverter which is controlled by end-closure checking means and is effective to reject faulty bags from a conveying path between the stations, the checking means comprising a single row of sensors for checking the presence of oblique edges of inwardly folded corner portions of the end closures and any deviation in the position of said oblique edges from a predetermined desired position. The said checking means in the prior application comprise two rows of sensors with four sensors in each row, the overall arrangement of the rows and sensors in the conveying path being such that each of the eight oblique edges of the corner portions of a bag comes within the sensing range of a respective one of the sensors and all eight oblique edges are checked simultaneously.

The present invention aims to provide a considerably simplified system.

According to the invention, only one row of stationary sensors (hereinafter referred to as oblique-edge sensors") is provided to sense the actual positions of the leading as well as the trailing oblique edges so that, as a bag is being moved along the conveying path, first the leading oblique edges and then the trailing oblique edges come within the sensing range of the oblique-edge sensors with means being provided to store fault impulses from the oblique-edge sensors and to transmit all fault impulses for any one bag simultaneously to actuating means for the diverter.

This development of the machine disclosed in the prior application makes use of the fact that, if the bag has no faults, the leading and trailing oblique edges of the inwardly folded corner portions are symmetrical to the longitudinal axis of the bag which is being conveyed side on. Half the number of sensors for the oblique edges, together with their associated amplifiers, switches and leads, can now be dispensed with and the adjustment of the sensors to bags of different sizes is considerably simplified. The fact that the fault impulses for any one bag are stored and then transmitted together at a predetermined instance ensures that the diverter is operated at the correct time, whether the faults ascertained by the sensors are at only the leading or only the trailing oblique edges.

Preferred means for storing the fault impulses and transmitting them together comprise electronic operating members or a relay with a holding device and a cam wheel revolving in phase with the machine and a stored fault impulse or impulses being transmitted at a predetermined time to the actuating means for the diverter, by closing a switch in the circuit of the relay or electronic operating members. The stored impulses can be erased by a second cam wheel or timing disc after each bag has been checked.

In a first embodiment of the prior application, the times during which correctly formed oblique edges are passing through are blanked out by timing means in the form of a timing disc which revolves in synchronism with the machine. It turns on and off a switch provided in the circuit for transmitting fault impulses to the diverter. In conjunction with the present invention, this timing disc can comprise first and second switching cams arranged on its periphery such that the first cam opens the switch shortly before the leading oblique edges, if they are correctly formed, reach the oblique-edge sensors, while the second cam closes the switch shortly after the trailing oblique edges, if they are correctly formed, have passed the said sensors. The relative angular position of the two switching cams can be adjustable to allow for bags of different sizes.

Although this embodiment is inexpensive, its accurate operation depends on the exact position of the bags in the direction of travel at a given time; experience shows that this may vary, with unfavorable effects on the checking results.

In a second embodiment of the prior application, the oblique-edge sensors are therefore preferably connected to the diverter-actuating circuit in dependence on the arrival of the leading and trailing longitudinal edges of the bag at the end-closure checking unit, in order to blank out the times when correctly formed oblique edges are passing through. For this purpose, two further stationary sensors (hereinafter referred to as control sensors") may be provided substantially in the transverse medial plane of the bag. The control sensors are symmetrical to the row of oblique-edge sensors and are spaced apart a distance such that one of them (influenced by the leading longitudinal edge of the bag) opens a first switch in the circuit transmitting the fault impulses to the diverter shortly before the correctly formed leading oblique edges arrive at the oblique-edge sensors, while the other control sensor (influenced by the trailing longitudinal edge of the bag) closes a second switch shortly after the correctly formed trailing oblique edges have passed the oblique-edge sensors.

The two control sensors are preferably adjustable in the direction of travel of the bag workpieces. This makes it possible for their switching impulses to be adapted to the various widths of the end closures of the bags and also for the tolerance range to be set within which they transmit the fault impulses detected by the oblique-edge sensors to the diverter actuating circuit.

The sensors used are preferably photoelectric detectors. The row of oblique-edge sensors open their associated switches in the diverter actuating circuit in response to a luminous signal and close them in response to a dark signal, while the control sensors close their associated switches in the said circuit in response to a luminous signal and open them in response to a dark signal.

An example of the invention will now be described with reference to the accompanying drawings, in which:

FIG. 1 is a diagrammatic plan view of the checking and rejecting apparatus of a bagmaking machine showing a workpiece being checked at the leading oblique edges of the inwardly folded comer portions.

FIG. 2 illustrates the position assumed by the workpiece of FIG. 1 when the trailing oblique edges of the inwardly folded corner portions are being checked, and

FIG. 3 is a circuit diagram of the FIG. 1 checking and rejecting apparatus.

The workpieces 5 for the bags that are being produced (only one workpiece is shown in FIGS. 1 and 2) are conveyed by means of lower rollers 6 which are located below the conveying plane and which are associated with upper rollers (not shown). These pairs of rollers guide the workpieces, in the direction of the arrow 8, past a checking unit 2 and into the vicinity of rejecting means comprising a diverter 25 for deflecting faulty workpieces out of the conveying path defined by the pairs of rollers 6.

The checking unit 2 is used to check the leading and trailing oblique edges 200-207 of the inwardly folded corner portions at the two cross-bottom closures 9 and 10 of the workpieces and to ascertain any errors in the positioning of these oblique edges.

The checking unit comprises four sensors 208-211 for sensing the oblique edges 200-207 of the corner portions and two control sensors 212, 213 for sensing the longitudinal edges 169, 169. The oblique-edge sensors are arranged in a row R-R at right angles to the direction 8 of travel of the workpiece 5, which is advanced transversely. Thus, as shown in FIG. 1, the leading oblique edges 200-203 first arrive at their respective sensors 208-211. Later, the trailing oblique edges 204-207 arrive at the same sensors as the workpiece is advanced (FIG. 2). The control sensors 212, 213 are arranged substantially in the transverse medial plane E-E of the workpiece and symmetrically in relation to the row R-R of obliqueedge sensors 208-211. The distance x between the control sensors 212, 213 is large enough to allow the front sensor 212 (as viewed in the conveying direction) to be influenced by the leading longitudinal edge 169 shortly before the leading oblique edges 200-203 come, if they are correctly formed, within sensing range of the oblique-edge sensors, and to allow the rear control sensor 213 to be influenced by the trailing longitudinal edge 169 shortly after the correctly formed trailing oblique edges 204-207 have left the sensing range of the oblique-edge sensors.

The oblique-edge sensors 2082l1 are fixed but slidably adjustable on a beam 214 attached to longitudinal walls 44, 45 of the machine frame. The fact that the sensors can be ad justed enables them to be accurately set to the various bag sizes that are encountered or, more precisely, to the various widths of the end closures. The control sensors 212, 213 are fixed but adjustable on a supporting member 215 attached to the longitudinal wall. By altering the spacing x between them, the control sensors may be set to the bag sizes in question and to the tolerance range within which the actual positions of the oblique edges are allowed to differ from a predetermined position. An increase in the spacing x results in a reduction in tolerance and a decrease in an increase in tolerance.

The oblique-edge sensors 208, 209 or 210, 211 for each end closure of the workpiece may be displaced symmetrically to the center line of the closure in question by spindles with leftand right-hand screw threads with the aid ofa scale calibrated to the widths of the end closures. When the bag length is changed, the mounting for either the right-hand or left-hand threaded spindle is moved together with half of the machine. Since the distance between the longitudinal edges of the workpiece and the roots of the adjacent oblique edges is always equal to half the width of the end closure, the control sensors 212 and 213 may also be adjustable by spindles with rightand left-hand screw threads with the aid ofa scale calibrated to the widths of the end closures.

The overall arrangement of the sensors 208213 corresponds to the predetermined desired position of the oblique edges of the inwardly folded corner portions. The function of the sensors is to ascertain any deviations of the actual positions of the oblique edges from their desired positions and to reject faulty workpieces by actuating the diverter 25 and causing them to be deflected out of the conveyor path.

An example of a circuit diagram for the checking and rejecting apparatus is given in FIG. 3. The sensors 208213 are preferably photodetectors. The sensors 208, 211,212 and 213 comprise a light source 26 on one side of the conveying plane 170 of the workpieces 5, a receiver 27 (photoelectric cell) on the other side, and an amplifier 28,28 (photoelectric cell amplifier). The light beam is interrupted and restored by the passage of successive workpieces. This principle is not applicable to the sensors 209 and 210 which sense the inner oblique edges 201, 202, 205 and 206, since these edges lie on the wall of the workpiece, i.e., they lie within the confines of the workpiece and do not coincide with its outline contour. The sensors 209, 210 are therefore in the form of reflection photodetectors receiving a light beamthat is reflected from a stationary specular reflection plate 216 which, as the workpiece is advanced, passes under the inner fold of the respective end closure. The sensors 208, 211,212, and 213 may also advantageously employ reflection detectors.

The amplifiers 28 of the oblique-edge sensors 2082l1 cause the respective switches 2l7--220 to close when the light beam is interrupted by the workpiece (dark signal) and to open in the presence of a luminous signal. The amplifiers 28 of the control sensors 212, 213 cause the respective switches 221, 222 to open in response to a dark signal and close in response to a luminous signal. The switches 217-220 are connected in parallel to the energizing circuit of a relay 57, while the switches 221, 222 are connected in parallel with one another and in series with the switches 217-220. Thus, each of the switches 217-220 is able to energize the relay 57 provided that at least one of the switches 221, 222 is closed. The relay 57 has an operating contact 58 and a holding contact 59. The contact 58 is in the circuit of a solenoid 60, in series with a release switch 53 which is closed briefly once per cycle of the machine by means ofa cam wheel 67 that turns in phase with the machine. The solenoid 60 forms part of actuating means (not shown in further detail), for the diverter 25 which the solenoid releases by means of a check lever 61 as soon as a faulty workpiece has to be deflected out of the conveying path.

A switch 63 is provided in the holding circuit of the relay 57 in series with the holding contact 59. The switch 63 is briefly opened by a cam wheel 64 once during each cycle of the machine, shortly after the cam wheel 67 has closed the switch 53.

If a workpiece 5 that is acceptable within the set tolerances passes through the checking unit 2, its front longitudinal edge 169 first interrupts the beam of the control sensor 213 and, after advancing a distance x, that of the control sensor 212. These dark signals cause the switches 221 and 222 to open. lmmediately afterwards, the leading oblique edges 200-203 of the inwardly folded corner portions enter the beam of the sensors 2082l1 which close their associated switches 217- 220 as a result of the dark signal but, since the switches 221 and 222 in the energizing circuit of the relay 57 were opened shortly beforehand, the relay 57 remains dead and the control means for the diverter 25 are consequently inoperative. The workpiece therefore remains on the conveyor. As the bag advances further, the trailing oblique edges 204-207 first restore the luminous signals from the sensors 2082l1 to open the associated switches 217-220 and terminate the current supply to the relay 57. Shortly afterwards, the rear longitudinal edge 169' restores the luminous signal from the control sensor 213 and, after a distance x, from the control sensor 212 to cause the associated switches 221, 222 to close, but his has no effect on the relay 57 because the switches 217-220 are already open. The diverter 25 therefore remains in an inoperative position where it keeps the workpieces on the conveyor so that the workpieces approved by the checking unit 2 are sent on to the store.

it will now be assumed that the workpiece has faults at the oblique edges 201 and 207, the faults having been caused by the preceding end-closure-forming station of the bagmakirig machine and resulting in the said oblique edges projecting beyond their normal position, as indicated in dotted lines atF in FIG. 2. When the faulty workpiece passes through the checking unit 2, the faulty projecting edge 201 at the leading side of the bag enters the light beam of the sensor 209 before the leading side edge 169 of the workpiece has entered the beam of the sensor 212 and thus before the latter has been able to open its associated switch 221. The switch 218 therefore closes the energizing circuit of the relay 57, with the result that the latter closes its operating contact 58 and holding contact 59. However, thefault signal from the sensor 209 is not yet passed on to the solenoid 60, but is stored by the holding contact 59 until the switch 53 in the circuit of the relay 57 is also closed by the cam wheel 67. As already mentioned, the cam wheel 67 briefly closes the switch 53 once per cycle of the machine. The cam is fixed to its drive shaft such that the switch 53 is closed shortly after the trailing oblique edges 204-207 have passed through the checking unit 2. The fault signal from the sensor 209 caused by the faulty oblique edge 201 is thus stored by the combined operation of the holding contact 59 and the cam wheel 67, until the trailing oblique edges 204-207 have also passed through the checking unit 2. In the present example, the light beam from the control sensor 213 is restored by the trailing longitudinal edge 169 of the bag, before the beam from the sensor 211 is restored by the faulty oblique edge 207. The switch 222 is therefore closed before the switch 220 is opened, with the result that the energizing circuit of the relay 57 is closed. However, since the relay has already gone over to a holding position in response to the fault signal from the sensor 209 caused by the faulty edge 201, the relay remains in its operative position. If there had been no previous fault signal, the fault signal produced by the faulty edge 207 would make the relay 57 respond.

When the trailing oblique edges 204'i20'7 have now also been checked by the sensors 208-211, the cam wheel 67 closes the switch 53, and thus the operating circuit of the relay 57, and the solenoid 60 pulls the check lever 61 so that the actuating mechanism for the diverter 25 is operated to reject the faulty bag from the conveying path. Preferably at the same time as the switch 53 is opened, but certainly not before then, the cam wheel 64 opens the switch 63 and terminates the holding action ofthe relay 57, so that the relay is ready to pick up another fault signal front a succeeding workpiece. If a workpiece happens to lie crooked, one of its corners will project beyond the predetermined position and, as is desired, the appropriate oblique-edge sensor will cause rejection of the crooked bag.

It will be appreciated that each illustrated workpiece 5 can eventually form two bags by being slit along the transverse medial line E.

We claim:

1. A machine for making bags having cross-bottom end closures, comprising an end-closure laying station, a delivery station and, disposed between them, a diverter which is controlled by end-closure checking means and is effective to reject faulty bags from a conveying path between the stations, the checking means comprising a single row of sensors for checking the presence of oblique edges of inwardly folded comer portions of the end closures and any deviation in the position of said oblique edges from a predetermined desired position, wherein only one row of stationary oblique-edge sensors is provided to sense the actual positions of the leading as well as the trailing oblique edges so that, as a bag is being moved along the conveying path, first the leading oblique edges and then the trailing oblique edges come within the sensing range of said oblique-edge sensors. means being provided to store fault impulses from the oblique-edge sensors and to transmit all fault impulses for any one bag simultaneously to actuating means for the diverter.

2. A machine according to claim 1, including timing means operating in synchronism with the machine for opening and closing a circuit that transmits the fault impulses to the diverter, wherein the timing means comprise first and second switching cams arranged so that the first cam opens a switch in the circuit shortly before the leading oblique edges, if they are correctly formed, arrive at the oblique-edge sensors, while the second cam closes the switch shortly after the trailing oblique edges, if they are correctly formed, have passed the said sensors.

3. A machine according to claim 2, wherein the relative angular position of the switching cams'is adjustable to allow for bags of different sizes.

4. A machine according to claim 1, including two stationary control sensors located transversely and symmetrically to the row of oblique-edge sensors at a spacing from one another such that the front control sensor, as viewed in the conveying direction of the bags, opens, when influenced by a leading longitudinal edge of the bag and shortly before the leading oblique edges, if correctly formed, reach the oblique-edge sensors, an associated first switch in a circuit that transmits the fault impulses to the diverter, while the rear control sensor, when influenced by the trailing longitudinal edge of the bag, closes an associated second switch in the said circuit shortly after the trailing oblique edges if they are correctly formed have passed the oblique-edge sensors.

5. A machine according to claim 4, wherein the control sensors are displaceable to adjust the spacing between them.

6. A machine according to claim 1, wherein the said storing and simultaneously transmitting means for the fault impulses comprise electronic operating members or a relay with a holding device and a cam wheel revolving in phase with the machine, said means being effective to transmit a stored fault impulse to the said actuating means for the diverter at a predetermined time by closing a switch in the circuit of the relay or electronic operating members, and wherein a second cam wheel is provided for sequentially erasing the stored impulses after each bag hasbeen checked.

A machine according to claim 4, wherein the sensors comprise photoelectric detectors, the oblique-edge sensors opening associated further switches in the said circuit in response to a luminous signal and closing them in response to a dark signal, while the control sensors close the said first and second switches in response to a luminous signal and open them in response to a dark signal.

8. A machine according to claim 1 in which the sensors are adjustable by means of spindles with rightand left-hand screw threads.

9. A machine according to claim 8, wherein the sensors are adjusted with the aid of scales calibrated to the widths of the end-closures.

10. A machine according to claim 4, wherein the sensors are adjustable by means of spindles with rightand left-hand screw threads. 

1. A machine for making bags having cross-bottom end closures, comprising an end-closure laying station, a delivery station and, disposed between them, a diverter which is controlled by endclosure checking means and is effective to reject faulty bags from a conveying path between the stations, the checking means comprising a single row of sensors for checking the presence of oblique edges of inwardly folded corner Portions of the end closures and any deviation in the position of said oblique edges from a predetermined desired position, wherein only one row of stationary oblique-edge sensors is provided to sense the actual positions of the leading as well as the trailing oblique edges so that, as a bag is being moved along the conveying path, first the leading oblique edges and then the trailing oblique edges come within the sensing range of said oblique-edge sensors, means being provided to store fault impulses from the oblique-edge sensors and to transmit all fault impulses for any one bag simultaneously to actuating means for the diverter.
 2. A machine according to claim 1, including timing means operating in synchronism with the machine for opening and closing a circuit that transmits the fault impulses to the diverter, wherein the timing means comprise first and second switching cams arranged so that the first cam opens a switch in the circuit shortly before the leading oblique edges, if they are correctly formed, arrive at the oblique-edge sensors, while the second cam closes the switch shortly after the trailing oblique edges, if they are correctly formed, have passed the said sensors.
 3. A machine according to claim 2, wherein the relative angular position of the switching cams is adjustable to allow for bags of different sizes.
 4. A machine according to claim 1, including two stationary control sensors located transversely and symmetrically to the row of oblique-edge sensors at a spacing from one another such that the front control sensor, as viewed in the conveying direction of the bags, opens, when influenced by a leading longitudinal edge of the bag and shortly before the leading oblique edges, if correctly formed, reach the oblique-edge sensors, an associated first switch in a circuit that transmits the fault impulses to the diverter, while the rear control sensor, when influenced by the trailing longitudinal edge of the bag, closes an associated second switch in the said circuit shortly after the trailing oblique edges if they are correctly formed have passed the oblique-edge sensors.
 5. A machine according to claim 4, wherein the control sensors are displaceable to adjust the spacing between them.
 6. A machine according to claim 1, wherein the said storing and simultaneously transmitting means for the fault impulses comprise electronic operating members or a relay with a holding device and a cam wheel revolving in phase with the machine, said means being effective to transmit a stored fault impulse to the said actuating means for the diverter at a predetermined time by closing a switch in the circuit of the relay or electronic operating members, and wherein a second cam wheel is provided for sequentially erasing the stored impulses after each bag has been checked.
 7. A machine according to claim 4, wherein the sensors comprise photoelectric detectors, the oblique-edge sensors opening associated further switches in the said circuit in response to a luminous signal and closing them in response to a dark signal, while the control sensors close the said first and second switches in response to a luminous signal and open them in response to a dark signal.
 8. A machine according to claim 1 in which the sensors are adjustable by means of spindles with right- and left-hand screw threads.
 9. A machine according to claim 8, wherein the sensors are adjusted with the aid of scales calibrated to the widths of the end-closures.
 10. A machine according to claim 4, wherein the sensors are adjustable by means of spindles with right- and left-hand screw threads. 